Lecture 10 - The Neurology Of Hearing And Balance Flashcards
What are the three parts of hearing system?
Outer ear, Middle ear and Inner ear
What are the structures of outer ear?
Pinna and External Auditory Canal
What are the functions of outer ear?
Sound waves are captured by the outer ear and funnelled through the external auditory canal to the tympanic membrane
Structures of Middle ear
Tympanic membrane, malleus, incus, stapes
What is the function of middle ear?
To convert the vibration in the air into some vibrations in the body so we can collect importante signals and process it
Sound waves can cause _______________ to vibrate.
Tympanic membrane
What are the functions of the three bones of the middle ear?
Transmit and amplify the vibrations to the oval window of the inner ear
What use the lever system principle in the middle ear, and what are the functions?
- Incus and stapes
- To save energy to have a higher efficiency using a lever system
- Amplify the signal and ensure the internal device can save space
What is the mechanism in middle ear?
The area in tympanic membrane is much larger than the oval window, so the pressure in the oval window is higher than that of tympanic membrane and that can amplify the pressure.
What can the bony structures in middle ear do?
It can selectively stop some parts to prevent the large sound from being sent to inner ear by tightening of tympanic membrane and increasing tendons in middle ear bones
What does inner ear convert?
Converts the mechanical signals into electrical signals
What is the structure for hearing in inner ear?
Cochlea
Why is cochlea needed?
- To save space
- To have a very long structure to capture different sounds with high-frequency sound travelling a shorter distance than low-frequency sound
Where in cochlea detect the high-frequency and low-frequency sounds?
- Sensors at the beginning of cochlea can detect high-frequency sound
- Sensors at the apex of cochlear (the end) will detect low-frequency sound
Where does liquid travel from and to in cochlea?
Liquid travels form oval window to round window in the cochlea, and that both structures are elastic that provides freedom to the perilymph inside
What is present in the cochlea?
Cochlear duct
What are the four hair cells in the cochlea?
3 outer hair cells and 1 inner hair cell
What are the functions of outer hair cells?
Backward connection from the brain and fine tune the sounds by pulling/ relieving the signals.
What are the functions of inner hair cell?
The main sensor for sound and transforming vibration into electrical signals
What are the two functions in inner ear?
- Fluid in the inner ear stimulate hair cells (nerve endings)
- Electrical impulses are sent from the hair cells along the auditory nerve to the brain
What is the procedure of converting mechanical waves into electrical signals?
- The mechanoreceptor induces influx of potassium ions (K+).
- Causing depolarization of cell.
- Further include influx of Calcium ions (Ca2+).
- Causing movement of vesicle to the membrane and release the neural transmitters, that will transform to electrical signals.
- The downstream processes are similar to neural synapse.
What can vibrate along the liquid environment in the inner ear?
Cilia
What can be detected by the brain if cilia can vibrate?
If cilia can vibrate, the small devices can be opened/ closed that cause change in the signals that can be detected by the brain.
What is energy transduction?
To transform some form of energy to another form of energy (and that goes through 5 kinds of energy in hearing)